Technical Field:
The system of the present application relates to a damper for an aircraft. In particular, the system of the present application relates to a lead/lag damper for a rotorcraft. The damper is particularly well suited for use in the field of rotary wing aircraft; however, other types of aircraft can implement the damper as well. It should be appreciated that even though the damper is illustrated herein with regard to an aircraft, one ordinary skill in the art with benefit of this disclosure will recognize that the damper can be implemented in applications other than an aircraft.
Description of Related Art:
Certain conventional rotorcraft can have multi-bladed rotor hub configurations that require lead/lag dampers to compensate for the acceleration and deceleration of each rotor blade about a rotor blade hinge axis. During forward flight of the rotorcraft, unequal drag forces on the advancing and retreating rotor blade positions typically cause oscillating forces that if left untreated, can negatively affect the rotorcraft. For example, untreated lead/lag oscillating forces can severely limit the life of structural components through fatigue. Furthermore, untreated lead/lag oscillating forces have been known to cause catastrophic results in a “ground resonance” phenomenon in which the oscillation frequency is similar to the resonant frequency of the aircraft on its landing gear.
Conventionally, lead/lag dampers utilize only elastomeric material to provide the spring rate; however, the spring rate of the elastomeric material tends to stiffen at low temperatures and soften at high temperatures. There is a need for an improved lead/lag damper that provides a more constant spring rate at extreme temperatures.